Just out of general curiosity. I have a trace amount of protein in my urine from slight kidney stress after being a T1 for a year and a bit. My sugars are well controlled and my endo isn't worried about it.

I had the signs before being diagnosed. There was the occasional day where my pinky and ring finger of my left hand felt like they were asleep. I still have a little in my toes. I keep a very close eye on my feet and check them regularly due to this. I just chalked it up to sleeping the wrong way on a nerve or something. Being a LADA I had a slow onset that I never really noticed all the signs. It wasn't until I went to the clinic for another issue that I said, while I'm here check for diabetes too.
Got misdiagnosed as a T2 and a year later had a 4 day hospital stay.

Regarding the trace amounts of protein it could be from two things. One your sugars being high causing mild DKA or through your diet. Extreme low carbing can cause protein to appear in your urine. A lot of fitness buff that follow a high protein low carb diet notice this even without diabetes. I forget the term off hand for it though.

In a related question, how does one know they're having trouble with neuropathy? I was diagnosed 4 years ago, and I'll be honest, every time I get numb in my feet from sitting on my legs, or my hands feel weird after sleeping on my arm, I get a little stab of fear.

The only way to really tell is when that numbness doesn't go away. As an example with my toes it's full time in a couple of places that there's no feeling. This happens even when you have not been sitting on them or sleeping on them. The simplest way is to ensure your doctor or endo is doing litmus tests and checking during your appointments. This should be part of any diabetics regular check ups.

I experienced neuropathy for a couple weeks before I was officially diagnosed - it was just one of the symptoms I'd had that led me to believe I had it. I also had increased urination, was really really thirsty, and had trouble sleeping.

Now I only experience neuropathy when my blood sugar gets above 500 mg/dL. Thankfully this has only happened a couple times recently.

My doctor does a tuning fork test. I know it sounds strange... but it seems really effective at detecting very early signs. She'll hit the tuning fork, touch it to my toes, and tell me to let her know when I stop feeling the vibration. I can't feel it over a period of time, she'll then push it to the skin on my hand to show that it was still vibrating. The difference is pretty small, but noticeable.